Which requirement is NOT mandated for fire extinguishers according to the Federal Motor Carrier Safety Administration?

The requirement that fire extinguishers must be constructed from fiberglass is not mandated by the Federal Motor Carrier Safety Administration (FMCSA). While fire extinguishers must meet certain performance and accessibility standards, the material from which they are constructed can vary. Extinguishers are commonly made of metal or composite materials and do not have to be specifically made from fiberglass.

On the other hand, the other requirements—being able to see if the extinguisher is fully charged, being readily accessible for use, and using an agent that does not freeze—are essential for ensuring that the extinguisher is effective in an emergency. A visible gauge allows drivers and operators to quickly check the charge status, while accessibility is crucial to ensure that the extinguisher can be quickly reached in case of a fire. Additionally, the use of a non-freezing agent ensures that the extinguisher remains functional even in cold weather conditions, which is particularly important in many operating environments.